In a number of technical applications, e.g., TFT metallization processes, one or multiple layers of different materials are deposited onto each other over a substrate. Typically, this is done in a sequence of coating or deposition processes, e.g., sputtering processes, wherein other processes like etching or structuring might also be provided before, between, or after the various deposition processes. For example, a multi-layer stack with a sequence of “material one”-“material two”-“material one” can be deposited.
In order to deposit a multiple layer stack, a number of configurations of processing chambers can be provided. For example, in-line arrangements of deposition chambers can be used as well as cluster arrangements of deposition chambers. A typical cluster arrangement comprises a central handling chamber and a number of processing or deposition chambers connected thereto. The coating chambers may be equipped to carry out the same or different processes. A typical in-line system includes a number of subsequent processing chambers, wherein processing steps are conducted in one chamber after the other such that a plurality of substrates can continuously or quasi-continuously be processed with the in-line system.
In technical applications such as the coating of glass substrates for displays, the edges of substrates are protected during a coating process, e.g., a sputter deposition process. An edge exclusion shield is used to protect the edges. Not only the substrates, but also the edge exclusion shields receive a coating during the coating process. As the coating on an edge exclusion shield becomes thicker, more and more particles may be re-emitted from the edge exclusion shield and deteriorate the quality of the substrate coating. A thick layer already deposited on the edge exclusion shield may have a shadowing effect, so the uniformity of the substrate coating can become worse.
If this happens, the deposition chamber is opened and the edge exclusion shield is replaced. This process may necessitate not only exchanging the edge exclusion shield, but also other components of the process kit such as additional shields, anodes etc. In a sputter substrate processing system, the target lifetime may be much longer than the time periods after which the edge exclusion shield needs replacement. The optimized lifetime of targets may therefore not come to full fruition. Moreover, the recovery time until the production can resume may be very long. For instance, re-establishing the vacuum in the chamber, but also other set-up processes, may take a long time that is hard to predict. Therefore, the overall output of the substrate processing system is negatively influenced.
Therefore, there is a need for improvement.